Plastic trial lens, its injection molded article and its molding apparatus

ABSTRACT

A plastic trial lens having a grip portion gripped when the lens is set in trial frames for trial lenses, an injection molded product for making the trial lenses, and a mold assembly for molding the injection molded product are provided. In the injection molded product molded by means of the mold assembly in an injection compression molding machine, a grip portion and a liquid guided and collected area are molded simultaneously with a lens portion on a periphery of the lens portion. When the injection molded product is dipped into hard coat liquid, the hard coat liquid is guided in the liquid guided and collected area to drip down and the remaining liquid without dripping down is collected in the liquid guided and collected area, thereby forming a coating film of uniform thickness on the lens portion. The plastic trial lens which is integrally provided with the grip portion is finished after the liquid guided and collected area is removed.

TECHNICAL FIELD

This invention relates to a plastic trial lens used for testing eyesightand the like of testees, an injection molded product for making theplastic trial lens, and a mold assembly for molding the injection moldedproduct for the plastic trial lens.

BACKGROUND ART

A trial lenses exchanged method, which is a subjective refraction tests,has been adopted for the prescription of glasses for selecting the mostsuitable lens for each user of glasses for some time. When the triallenses exchanged method is conducted, a testee wears trial frames fortrial lenses. Many kinds of trial lenses with various spherical dioptersand astigmatic diopters and the like selected among a set of triallenses are fitted in trial frames, thereby selecting the most suitablelens for each testee. A trial lens used in the trial lenses exchangedmethod has a grip portion on a periphery of a lens portion. By grippingthe grip portion, the trial lens is set in and taken off from the trialframes.

A conventional trial lens is mainly made of glass. The trial lens ismanufactured by attaching a holder ring member with a grip portion onthe periphery of the lens cut (edge-filed) into the fixed size (JapaneseUtility Model Laid-open No. Hei 4-22902). Some conventional trial lensesare plastic, but the manufacturing process after cutting is the same asthat of glass trial lenses.

Besides manufacturing lenses, the conventional trial lens manufacturerequires the process of manufacturing members for grip portions withdifferent materials from the lenses and attaching the members on lenses,which takes a lot of time and labor.

Members for grip portions are made of metal in view of durability andeasy operation, which causes the disadvantage that a trial lens is heavyas a whole. In complicated prescriptions for glasses for astigmatism,glasses for both far vision and near vision and the like, trial testsare conducted by setting more than one trial lenses one on another intrial frames so that the ears and nose of a testee get a heavy weight,which causes another disadvantage that the trial frames are easy to slipoff. The diameter of the trial lens is small so that after-processingsuch as edge-filing and holder ring attaching is difficult. The gripportion is disposed at the fixed angle, for example, at the upper rightor at the upper left of the lens in consideration of setting work intrial frames. In a trial lens with differences between the top and thebottom and between the right and the left, such as a progressivemultifocal lens and a lens for an astigmatism, when a holder ring with agrip portion is attached on the periphery of the trial lens, precisepositioning of the above fixed angle concerning the grip portion isrequired in accordance with an optical layout in the design of the lensabout an optical center position and the like, which makes the attachingprocess of the holder ring difficult in a trial lens with a shortdiameter. Moreover, when the holder ring with the grip portion iscaulked too strongly on the periphery of the lens, in a plastic lens,this situation causes an optical surface to be deformed, which bringsabout optical distortion and the like.

An object of the present invention is to provide a plastic trial lens,in which the process of manufacturing a member for a grip portion withdifferent materials from a lens and attaching the member on the lens isomitted, the whole trial lens is more light-weight and the preciselayout of the grip portion in relation to the lens portion is obtained,and an injection molded product to make the plastic trial lens, andmoreover, a mold assembly to mold the injection molded product.

DISCLOSURE OF THE INVENTION

A plastic trial lens according to the present invention is provided witha lens portion and a grip portion integrally formed on a periphery ofthe lens being gripped when the lens portion is set in trial frames fortrial lenses, the grip portion being molded simultaneously with the lensportion.

The trial lens according to the present invention is plastic, in whichthe grip portion is integrally molded with the lens portion. The lensportion and the grip portion are molded out of the same synthetic resin,the grip portion being molded simultaneously with the lens portion,which omits the process of attaching a member for the grip portion onthe lens portion. The grip portion is formed out of the same syntheticresin as the lens portion so that the whole trial lens is lightweight.The grip portion is integrally molded with the lens portion after beingpositioned in a mold assembly so as to be formed in the fixed positionof the lens portion, and hence the grip portion is disposed in relationto the lens portion in a fixed position accurately laid out.

An injection molding method, an injection compression molding method ora casting method (cast molding method) can be adopted to manufacture theabove-described plastic trial lens in which the lens portion and thegrip portion are integrally molded.

However, the casting method uses thermosetting resins (diethylene glycolbisuallyl carbonate is typical) for materials. The polymerizationshrinkage percent of thermosetting resin is as large as about 14percent. Therefore, the difference between a lens shape in design and areal mold transfer shape is large so that extremely high manufacturingtechnology is required to make precision mold transfer of a moldedproduct attain the high precision required for the trial lens. Inaddition, molding a plastic lens by means of the casting method requiresa molding time from 12 to 24 hours to precisely control thepolymerization of the resin for the materials. As a result, one cycle ofmolding time becomes long, thus making mass-production of trial lensescostly. For the reasons stated above, it is preferable that the plastictrial lens is molded by means of the injection molding method or theinjection compression molding method in which any disadvantage asdescribed above does not occur.

When the plastic trial lens is molded by means of the injection moldingmethod or the injection compression molding method, the thermoplasticresin used for the materials is such as a PMMA (polymethyl methacrylate)system resin or a PC (polycarbonate) system resin.

A holder ring can be attached on the periphery of the lens portion ofthe plastic trial lens, but it is preferable that an edge portioninstead of the holder ring is integrally provided on the periphery ofthe lens portion, the edge portion being molded simultaneously with thelens portion.

Using the edge portion instead of the holder portion helps the triallens to be more lightweight and omits a member for the holder ring. Inaddition, the process requiring the holder ring to be caulked on theperiphery of the lens portion is unnecessary, which secures a highoptical precision of the lens portion.

The plastic trial lens according to the present invention can be aprogressive multifocal lens with a portion for far vision, a portion fornear vision and a progressive portion between the portion for far visionand the portion for near vision or a lens for an astigmatism. Thepresent invention is applicable to both a single vision lens and amultifocal lens which has a portion for near vision and a portion forfar vision but no progressive portion.

When the trial lens is a progressive multifocal lens, it is preferablethat the lens is provided with a mark indicating the direction of ahorizontal datum line and a grip portion shifting to the right or theleft from the center between the right portion and the left portion ofthe lens portion on the periphery of the lens portion according to thelens for a right eye or for a left eye.

Thus, the distinction between a lens for a right eye and a left eye ineach progressive multifocal trial lens and the horizontal direction areclearly known with the position of the grip portion and the mark. As aresult, while distinguishing the trial lens for a right eye from thatfor a left eye, the position of revolving direction of the round shapedlens portion as a whole in each trial lens is accurately fixed so thatthe trial lens can be fitted in the trial frames in an accurateposition.

Also, a diopter measuring position in the portions for far vision andfor near vision in the lens portion or a layout of optical center can beeasily known with the grip portion and the mark.

The mark for indicating a horizontal datum line can be provided afterthe lens is molded by means of injection molding and also moldedsimultaneously with the lens portion and the grip portion. If the markis molded simultaneously as described above, a manufacturing process iscut, thus improving the manufacturing efficiency.

When the mark is molded simultaneously with the lens portion and thegrip portion, the mark is formed as an indented portion or a projectedportion in the lens portion. However, it is preferable that the mark isnot a projected portion but an indented portion. If the mark is aprojected portion, the projected portion becomes a hindrance, forexample, it catches in the trial frames when the trial lens is fitted inthe trial frames. The indented portion as the mark can be indented fromone surface of the lens portion and also cut deep in an insidediametrical direction of the lens portion. Moreover, it is possible tocombine the above two ways.

Many sorts of diopters are provided in the aforesaid progressivemultifocal lens. The present invention is applicable to trial lenseswith various diopters, to take an example, a lens with 0.00 diopter in aportion for far vision in which the diopter for near vision is fixedonly in a portion for near vision. This type of trial lens can be set inthe trial frames with a single vision trial lens for far vision or nearvision one on another.

An injection molded product for making the plastic trial lens accordingto the present invention is provided with a lens portion, a liquidguiding and collecting area integrally formed on a periphery of the lensportion in which coating liquid flowing down on the surfaces of the lensportion is guided and collected when the lens is dipped into and pulledup from the coating liquid, and a grip portion gripped when the lensportion is set in the trial frames after the liquid guiding andcollecting area is removed. The liquid guiding and collecting area andthe grip portion are molded simultaneously with the lens portion.

The dipping process requiring that the injection molded product bedipped into the coating liquid is conducted to form a coating film madeout of the hard coating liquid on surfaces of the trial lens. The hardcoating film improves the abrasion-resistance and durability of thetrial lens.

When the injection molded product with the lens portion is dipped intoand pulled up from the coating liquid, the coating liquid flows down onthe surfaces of the lens portion, while a coating liquid collectingportion is formed at the bottom of the lens portion. This causes adifference in the thickness of a coating film between a part nearby anda part far from the liquid collecting portion, thus changing thecurvature of a lens surface, which sometimes affects the lens diopter.As a result, serious disadvantages may occur from the viewpoint of theprecision of the trial lenses.

In the present invention, when the lens portion is molded by means ofthe injection molding method or the injection compression moldingmethod, the liquid guiding and collecting area, as well as the gripportion, is molded at the same time on the periphery of the lensportion. The liquid guiding and collecting area is formed to guide thecoating liquid flowing down on the surfaces of the lens portion when theinjection molded product is dipped into and pulled up from the coatingliquid, and to collect the remaining liquid without dripping.Consequently, a liquid collecting portion is formed in the liquidguiding and collecting area so as to ease the effects on the lensportion by the liquid collecting portion, which virtually assures theuniformity in thickness of the coating film.

When the liquid guiding and collecting area having the above-describedeffects is formed in the injection molded product for the trial lens, inthe present invention, the liquid guiding and collecting area as well asthe grip portion is simultaneously molded on the periphery of the lensportion, thereby facilitating the molded process.

The shape of the liquid guiding and collecting area is optional if thecoating liquid flowing down on the surfaces of the lens portion can beguided and the remaining liquid without dripping down can be collectedin the area when the injection molded product is dipped in and pulled upfrom the coating liquid, for example, a bar shape extending in anoutside diametrical direction of the lens portion (downward when pulledup from the coating liquid) or a fan shape with a small projection in anoutside diametrical direction and two long sides extending in acircumferential direction is available.

The liquid guiding and collecting area is, however, removed when thelens portion is set in the trial frames by gripping the grip portionafter the trial lens is finished. In order to facilitate the removingprocess and keep the liquid collecting portion formed of the coatingliquid flowing down on the surfaces of the lens portion away from thelens portion, the liquid guiding and collecting area is preferablyshaped into a bar extending in an outside diametrical direction.

The grip portion and the liquid guiding and collecting area integrallymolded on the periphery of the lens portion can be formed in an optionalpositional relationship, but preferably the grip portion and the liquidguiding and collecting area are formed opposite to each other on theperiphery of the lens portion.

As a result, when the injection molded product is dipped into thecoating liquid, by placing the liquid collecting and guiding areadownward and the grip portion upward, the injection molded product isdipped into the coating liquid by supporting the grip portion with asupporting utensil such as a clip. Moreover, when the injection moldedproduct is pulled up from the coating liquid, the coating liquidcollecting portion is formed in the liquid guiding and collecting areathat is disposed downward, thereby forming a coating film of a uniformthickness on the surfaces of the lens portion as predetermined.

In the above case, the grip portion is used to be gripped when the lensportion is set in the trial frames and also used as a portion to besupported with the supporting utensil when the injection molded productwith the lens portion is dipped into the coating liquid.

In the injection molded product, one lens portion can be formed or morethan one lens portion can be formed in two-dimensional orthree-dimensional positional relationship, that is, the injection moldedproduct can make one lens or more than one lens.

In the injection molded product for making more than one lens,preferably more than one lens portion are coupled to each other by meansof a coupling portion, the coupling portion being provided with aportion supported when the lens portions are dipped into the coatingliquid, and the liquid guiding and collecting area is formed on anopposite side to the supported portion on a periphery of each lensportion.

Consequently, each lens portion is dipped into the coating liquid bysupporting the supported portion disposed upwardly with the supportingutensil. Thus, all lens portions are dipped into the coating liquid atthe same time and the liquid collecting portion is formed in each liquidguiding and collecting area, since each liquid guiding and collectingarea is disposed downward when each lens portion is pulled up from thecoating liquid.

In the above-described injection molded product for making the triallens, the grip portion and the liquid guiding and collecting area areseparately formed. However, an injection molded product with a portionserving both as a grip portion and a liquid guiding and collecting areacan be manufactured.

In other words, this type of injection molded product for the trial lensis provided with a lens portion and a grip portion molded simultaneouslywith the lens portion on the periphery of the lens portion being grippedwhen the lens portion is set in trial frames. Since the grip portion isdisposed downward when the lens portion is dipped into the coatingliquid, the grip portion also serves as a liquid guiding and collectingarea in which the coating liquid flowing down on surfaces of the lensportion is guided and collected when the lens portion is pulled up fromthe coating liquid.

The injection molded product for the trial lens can be an injectionmolded product for a progressive multifocal lens with a portion for farvision, a portion for near vision and a progressive portion between theportion for far vision and the portion for near vision or an injectionmolded product for a lens for an astigmatism. In addition, the injectionmolded product is applicable to both a single vision lens and amultifocal lens which has a portion for far vision and a portion fornear vision but no progressive portion.

When a progressive multifocal lens is obtained from the injection moldedproduct, as described above, the progressive multifocal lens has 0.00diopter in a portion for far vision in which the diopter for near visionis fixed only in a portion for near vision. This type of trial lens canbe set in the trial frames with a single vision trial lens for farvision or near vision one on another.

When the lens portion in the injection molded product is a progressivemultifocal lens portion with a portion for far vision, a portion fornear vision and a progressive portion between the portion for far visionand the portion for near vision, the grip portion is preferably formedon the periphery of the side of the portion for far vision out of bothsides of portions for far vision and near vision in the lens portion.When the grip portion is formed on the periphery of the side of theportion for near vision in the lens portion, a groove depending on thesectional shape of the portion for near vision is formed in a boundarybetween an edge portion and the portion for near vision in the lensportion so that the coating liquid is likely to be collected in thegroove. When the grip portion is formed on the periphery of the side ofthe portion for far vision in the lens portion, the above-mentioneddisadvantage does not occur, thus securing high optical precision of thelens portion.

The injection molded product for the trial lens, in which the gripportion serves as the liquid guiding and collecting area, is providedwith a supported portion supported with a supporting utensil when theinjection molded product is dipped into the coating liquid. Thesupported portion can be formed in an optical positional relationship tothe grip portion, but preferably the supported portion is formed on theopposite side to the grip portion on the periphery of the lens portion.

As a result, when the injection molded product is dipped into thecoating liquid, by placing the grip portion downward and the supportedportion upward, the injection molded product is dipped into the coatingliquid by supporting the supported portion with a supporting utensilsuch as a clip. Moreover, when the injection molded product is pulled upfrom the coating liquid, the coating liquid collecting portion is formedin the grip portion that is disposed downward, thereby forming a coatingfilm of uniform thickness on the surfaces of the lens portion aspredetermined.

Preferably, the supported portion is molded simultaneously with the lensportion and the grip portion, which can shorten the manufacturingprocess.

The shape of the supported portion is optional if it can be surelysupported with the supporting utensil, for example, a bar shapeextending in an outside diametrical direction of the lens portion or afan shape with a small projection in an outside diametrical directionand two long sides extending in a circumferential direction isavailable.

The supported portion is, however, removed when the lens portion is setin the trial frames by gripping the grip portion after the trial lens isfinished. In order to facilitate the removing process, the supportedportion is preferably shaped into a bar extending in an outsidediametrical direction of the lens portion and having a small connectingarea with the lens portion.

A mold assembly for molding the injection molded product for the plastictrial lens according to the present invention is provided with two moldsto be parted, a pair of inserts disposed in each of the molds which forma cavity for molding the plastic trial lens by a molten synthetic resinfilled therein when the molds are mold-closed. The cavity includes alens molded portion to mold the lens portion of the trial lens and agrip molded portion to mold the grip portion on the periphery of thelens portion being gripped when the lens portion is set in trial frames.

In the mold assembly, the cavity between a pair of the inserts includesthe lens molded portion and the grip molded portion. Therefore, when themolten synthetic resin is filled in the cavity, the lens portion and thegrip portion of the trial lens are molded at the same time.

The molds to be parted in the mold assembly consist of a top mold and abottom mold or a right mold and a left mold. In other words, the moldassembly can be structured both vertically and horizontally.

The injection molded product for the trial lens molded in the moldassembly can be the injection molded product for a progressivemultifocal lens with a portion for far vision, a portion for near visionand a progressive portion between the portion for far vision and theportion for near vision or the injection molded product for a lens forastigmatism. In addition, the injection molded product is applicable toboth a single vision lens and a multifocal lens which has a portion forfar vision and a portion for near vision but no progressive portion.

The mold assembly can be used for molding more than one progressivemultifocal trial lenses with different additions. In this case, it ispreferable that the mold assembly is provided with more than one set ofa pair of inserts, the lens portion molded between more than one set ofthe inserts is a progressive multifocal lens portion with a portion forfar vision, a portion for near vision and a progressive portion betweenthe portions for far vision and for near vision, a spacer for adjustingthe thickness of the lens is disposed on the back side of one insert outof a pair of the inserts opposite to each other, and more than onespacer having different thicknesses are provided in more than one set ofthe inserts so that more than one progressive multifocal lens withdifferent additions are molded by means of the spacers having differentthicknesses.

A concave surface side of the progressive multifocal lens portion thatis a meniscus lens is a spherical surface with a fixed curvature. By thecurvature of a convex surface side which is an aspheric surface, theshape of the lens surface and the diopter change. As the addition isenlarged, the thickness of the center of the lens becomes large and thevolume of the lens increases. When more than one lens portion withdifferent additions are molded in the mold assembly at the same time, alarge difference in volume among the lens portions affects the moldingconditions, which makes it difficult to secure high optical precisionfor all the lens portions. In the present invention, to virtually fixthe volume of each lens portion regardless of the addition, first anintermediate addition is set, then the lens thickness of the lensportion with the intermediate addition is found and this thicknessbecomes a standard against which the thickness of each of the other lensportions with different additions is redesigned. In a lens portion withan addition smaller than the above intermediate value, the volume of thelens is increased, while in a lens portion with an addition larger thanthe above intermediate value, the volume of the lens is decreased.

With regard to the spacer, spacers with thicknesses larger than andsmaller than the spacer with the intermediate thickness are made so asto obtain less portions with additions larger than and smaller than theintermediate addition. The spacers having different thicknesses aredisposed on the back of the insert on one side out of more than one setof the inserts so that a difference in capacity (volume of the lensportion) among more than one cavity to mold more than one sort ofprogressive multifocal lens portion with different additions isadjusted. As a result, molding conditions in each trial lens portionformed by filling the molten synthetic resin in the cavity become almostuniform, which raises the mold transfer efficiency in each cavity andensures high optical precision.

In the mold assembly according to the present invention, a back insertcan be disposed on the back side of one of a pair of the inserts and theposition of a molded surface of the lens portion in one insert inrelation to the other insert can be established by the length of theback insert.

The position of the molded surface of the lens portion in one insert inrelation to the other insert is established by the length of the backinsert. Therefore, only the molded surface of the lens portion isrequired to have high-precision finishing in one insert, which canfacilitate the work of manufacturing and processing the above oneinsert.

The cavity formed between a pair of the inserts can include an edgemolded portion to mold the edge portion serving as the holder ring onthe periphery of the lens portion.

In this case, in the plastic trial lens obtained from the injectionmolded product, the holder ring does not need to be attached on theperiphery of the lens portion, thus simplifying the manufacturingprocess of the trial lens.

A grip molded portion to mold the grip portion on the periphery of thelens portion can be formed in relation to a lens molded portion to moldthe lens portion in an optional circumferential directional position.However, preferably, the grip molded portion is formed between a gatefrom which molten synthetic resin flows into the cavity and the lensmolded portion in the cavity.

When the molten synthetic resin flows into the cavity from the gate, themolten synthetic resin is filled in the lens molded portion through thegrip molded portion so that distortion by filling the molten syntheticresin is easy to break out in a portion of resin near the gate, but thedistortion occurs in the portion of resin filled in the grip moldedportion, which prevents distortion from breaking out in a portion ofresin filled in the lens molded portion, thus securing a high precisionof the lens.

A pair of the inserts to form the cavity can be formed with each memberdisposed in each mold to be parted, but preferably a pair of the insertsrespectively include an inner insert member to mold the lens portion andan outer insert member disposed on the outside of the inner insertmember to mold the grip portion.

Consequently, when more than one kind of trial lenses with differentadditions in the lens portions, which are provided with the gripportions integrally on the periphery of the lens portions, aremanufactured, only the inner inserts are exchanged and the outer insertcan be used in common for more than one kind of the trial lens.

Materials for members composing the mold assembly can be metal, ceramicor glass, and in addition, the above different kinds of materials can beused for more than one member.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view of the principal portion of a moldassembly of an injection molding machine;

FIG. 2 is a schematic plane view taken along the A-A line in FIG. 1;

FIG. 3 is an explanatory view showing the process of coating aninjection molded product provided with a liquid guiding and collectingarea molded by means of the mold assembly in FIG. 1 and FIG. 2;

FIG. 4 is an explanatory view showing the process of setting a plastictrial lens in trial frames for trial lenses, the plastic trial lensbeing manufactured by removing the liquid guiding and collecting areafrom the injection molded product in FIG. 3;

FIG. 5 is an explanatory view showing the process of coating aninjection molded product in which more than one lens portions arecoupled with a coupling portion;

FIG. 6 is an explanatory view showing the process of setting a triallens in trial frames for trial lenses according to an embodiment inwhich a grip portion serves as a liquid guiding and collecting area;

FIG. 7 is a schematic view of an injection molded product to obtain thetrial lens in FIG. 6;

FIG. 8 is a sectional view taken along the B-B line in FIG. 7;

FIG. 9 is a perspective view showing a whole injection molded product inwhich more than one injection molded product in FIG. 7 are formed;

FIG. 10 is an explanatory view showing the process of coating more thanone injection molded product in FIG. 7 obtained from the injectionmolded product in FIG. 9;

FIG. 11 is a sectional view taken along the C—C line in FIG. 10;

FIG. 12 is a vertical sectional view of a mold assembly for injectioncompression molding to manufacture the injection molded product in FIG.9;

FIG. 13 is a sectional view taken along the D—D line in FIG. 12;

FIG. 14 is a fragmentary enlarged view of FIG. 13 showing a pair ofinserts forming a cavity; and

FIG. 15 is a schematic view showing a spacer and the surroundings incase of molding more than one kind of progressive multifocal lens withdifferent additions by means of the spacer for adjusting a thicknessdisposed on the back side of one insert out of a pair of the inserts.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is explained more in detail in accordance with theaccompanying drawings. A mold assembly in an injection molding machineto mold an injection molded product for making a plastic trial lensincludes a top mold 1 and a bottom mold 2, both of which a parting linePL divides as illustrated in FIG. 1. The top mold 1 contains an outerinsert member 4 in the center of which an inner insert member 3 is fixedand an insert base 5 having mounted thereunder the outer insert member4, all of which are slidably guided inside an upper insert guide 6. Thebottom mold 2 contains an outer insert member 8 in the center of whichan inner insert member 7 is fixed, and an insert base 9 having mountedthereon the outer insert member 8, all of which are slidably guidedinside a lower insert guide 10.

The insert base 5 in the top mold 1 is coupled with a piston rod 11which extends in a downward direction from an upper cylinder (notshown). When the piston rod 11 retracts (goes up), the insert base 5abuts on a back insert 12. The insert base 9 in the bottom mold 2 iscoupled with a piston rod 14 which extends in an upward direction from alower cylinder 13. When the piston rod 14 retracts (goes down), theinsert base 9 abuts on a mold plate 15. In this position, the outerinsert 8 and the like become fixed.

The inner and outer insert members 3 and 4 in the top mold 1 form aninsert 1A and the inner and outer insert members 7 and 8 in the bottommold 2 form an insert 2A. When the top mold 1 and the bottom mold 2 aremold-closed, between a pair of the insert 1A and the insert 2A disposedvertically a cavity 16 for molding the injection molded product for thetrial lens is formed.

As illustrated in FIG. 2, the cavity 16 is composed of a lens moldedportion 16A, a grip molded portion 16B, and a liquid guiding andcollecting area molded portion 16C. The grip molded portion 16B isprovided with a runner 17, the runner 17 being linked to a sprue, thesprue being connected to an injection nozzle of the injection moldingmachine.

As shown in FIG. 1, the inner insert member 3 in the top mold 1 and theinner insert 7 in the bottom mold 2, both of which are verticallydisposed opposite to each other, form the lens molded portion 16A. Also,the outer insert member 4 in the top mold 1 and the outer insert 8 inthe bottom mold 2, both of which are vertically disposed opposite toeach other, form the grip molded portion 16B and the liquid guiding andcollecting area molded portion 16C.

When the top mold 1 and the bottom mold 2 are mold-closed with aclamping cylinder, heated molten synthetic resin is injected from theinjection nozzle into the sprue and the molten synthetic resin is filledin the sprue, the runner 17 and the cavity 16, and then gradually coolsand solidifies.

Subsequently the top mold 1 and the bottom mold 2 are mold-opened fromthe parting line PL, and upon operation of ejecting means (not shown) aprimary injection molded product 18 in FIG. 2 is taken out. In the samepositional relationship with the lens molded portion 16A, the gripmolded portion 16B, and the liquid guiding and collecting area moldedportion 16C, the primary injection molded product 18 is integrallyformed with a grip portion 18B and a liquid guiding and collecting area18C in an opposite position to each other on a periphery of a lensportion 18A. The grip portion 18B is linked to a portion 19 formed inthe runner 17, the portion 19 being linked to a portion formed in thesprue. The grip portion 18B, the liquid guiding and collecting area 18Cand the like are molded simultaneously with the lens portion 18A.

The primary injection molded product 18 manufactured as described aboveis cut between the grip portion 18B and the portion 19, thereby making asecondary injection molded product 18′ shown in FIG. 3 which is composedof the lens portion 18A, the grip portion 18B, and the liquid guidingand collecting area 18C. After completion of predetermined treatmentssuch as washing, the secondary injection molded product 18′ is treatedby dipping, that is, the secondary injection molded product 18′ isdipped into a hard coating liquid 21 that is, for example, a silicon oracrylic coating liquid. Coating is conducted by placing the grip portion18B upward and the liquid guiding and collecting area 18C downward, thensupporting the grip portion 18B that is disposed upward with asupporting utensil 20 such as a clip.

The secondary injection molded product 18′ is pulled up, after beingdipped into the hard coating liquid 21 at least above the boundary partbetween the lens portion 18A and the grip portion 18B. At this time, asurplus of hard coating liquid covering surfaces of the lens portion 18Aflows down on the lens surfaces and is guided to the liquid guiding andcollecting area 18C for dripping down.

Furthermore, a small amount of the remaining liquid without drippingdown forms a liquid collected portion in the liquid guiding andcollecting area 18C, but not in the lens portion 18A.

Next, by UV-hardening (hardening by ultraviolet irradiation) andheat-drying the secondary injection molded product 18′, the surfaces ofthe lens portion 18A are covered with a coating film made from a hardcoating liquid. As illustrated in FIG. 4, the liquid guiding andcollecting area 18C is removed from the lens portion 18A by cutting andthe like. A holder ring 22 is attached on the periphery of the lensportion 18A and, moreover, a label 23 indicating the diopter of thetrial lens and other information is stuck to the grip portion 18B,thereby finishing a plastic trial lens 18″.

An edge portion made of a thick portion and the like, instead of theholder ring, can be molded on the periphery of the lens portion 18Asimultaneously with the lens portion 18A, the grip portion 18B and theliquid guiding and collecting area 18C. Even when a holder ring isattached on the periphery of the lens portion 18A by caulking withoutforming the edge portion on the periphery of the lens portion 18A, theholder ring 22 does not need to be strongly caulked, since the gripportion 18B is integrally molded in the predefined laid-out position ofthe lens portion 18A.

Instead of using the label 23, the indication of lens diopter and otherinformation on the grip portion 18B can be made with a mark engraved ona mold component member at the time of molding by means of the moldassembly in the injection molding machine

As shown in FIG. 4, the trial lens 18″ is exchangeably set in trialframes for trial lenses 24 for testing eyesight and the like of testees.The trial lens 18″ is set in the trial frames 24 and removed therefromby gripping the grip portion 18B.

A trial lens according to the above-described embodiment is aprogressive multifocal lens with 0.00 diopter in a portion for farvision and an outside diameter of 35 millimeter. The primary injectionmolded product 18 can be molded for making more than one lens with morethan one progressive multifocal lens portion 18A. In this case, morethan one lens portion 18A needs to be a progressive multifocal lensportion. Additions of the progressive multifocal lens portion 18A arefive kinds ranging from 1.00 diopter to 3.00 diopter at an interval of0.5 pitch as required, and two lens portions 18A with the same additioncan be molded at every shot by the injection molded machine.Consequently, a total of ten lens portions 18A with the whole range ofdiopters having the necessary five kinds of additions can be molded atthe same time at one shot, which can facilitate inventory management ofthe trial lens 18″ manufactured from the lens portion 18A.

According to the present embodiment described above, the trial lens 18″is plastic and integrally formed with the grip portion 18B on theperiphery of the lens portion 18, the grip portion 18B being grippedwhen the trial lens 18″ is set in the trial frames 24. Since the gripportion 18B is molded simultaneously with the lens portion 18A, theprocess of manufacturing members for grip portions with differentmaterials from lenses and attaching the members on lenses is omitted,which facilitates the whole trial lens manufacturing process.

The grip portion 18B is not metal, but formed of the same syntheticresin as the lens portion 18A, thus making the trial lens 18″ morelightweight as a whole. Furthermore, the grip portion 18B is integrallymolded with the lens portion 18A, which differs from the process when agrip portion is attached to a lens portion by means of caulking a holderring provided with a grip portion on the periphery of the lens portion.

Consequently, the accurate position of the grip portion 18B laid out inrelation to the lens position 18A is obtained, securing high opticalprecision of the lens portion 18A. Even when the holder ring 22 isattached on the periphery of the lens portion 18A, the holder ring 22does not need to be strongly caulked on the lens portion 18A, therebypreserving high optical precision of the lens portion 18A.

The plastic trial lens 18″ according to the present embodiment can bemanufactured by means of the injection molding method or the injectioncompression molding method. Even if the molten synthetic resin for thematerial shrinks when cooling and solidifying by a high-pressureinjection force or compression force applied at the time of molding, themold transfer precision is sufficient to attain the high precisionrequired for the trial lens. Moreover, one cycle of the molding processby the injection molding method or the injection compression moldingmethod is extremely shorter than that by a conventional casting method,which makes the mass-production of the trial lenses possible andincreases the manufacturing efficiency.

In addition, the injection molded product 18′ for making theabove-described trial lens 18″ is provided with the liquid guiding andcollecting area 18C. When the injection molded product 18′ is dippedinto and pulled up from the hard coating liquid 21, the hard coatingliquid flowing down and dripping on the surfaces of the lens portion 18Acan be guided to the liquid guiding and collecting area 18C. At the sametime, a small amount of the remaining liquid without dripping down formsa liquid collected portion in the liquid guiding and collecting area18C, which assures the uniformity of the thickness of the coating filmcovering the surfaces of the lens portion 18A without being affected bythe liquid collected portion.

Since the liquid guiding and collecting area 18C, as well as the gripportion 18B, is integrally molded on the periphery of the lens portion18A, the liquid guiding and collecting area 18C is molded simultaneouslywith the lens portion 18A.

The liquid guiding and collecting area 18C is shaped into a barextending in an outside diametrical direction of the lens portion 18A.Consequently, the liquid collected portion formed with the remainingliquid without dripping is isolated from the lens portion 18A, thussurely making the thickness of the coating film formed on the lensportion 18A more uniform. In addition, the trial lens 18″ is completedby removing the liquid guiding and collecting area 18C from theinjection molded product 18′. The liquid guiding and collecting area 18Cis shaped into a bar with a small connecting area with the lens portion18A, which facilitates the removing process.

The grip portion 18B and the liquid guiding and collecting area 18C areformed opposite to each other on the periphery of the lens portion 18A.The injection molded product 18′ is dipped into and pulled up from thehard coating liquid 21 placing the liquid guiding and collecting area18C downward by supporting the grip portion 18B that projects upwardwith the supporting utensil 20. Therefore, the grip portion 18B is usedboth as a grip when the trial lens 18″ is set in the trial frames 24 andas a support when the injection molded product 18′ is dipped into thehard coating liquid 21.

FIG. 5 schematically illustrates an injection molded product 28according to another embodiment of the present invention. The injectionmolded product 28 is provided with two pieces of a lens portion 28A.These two lens portions 28A are coupled through a grip portion 28B bymeans of a coupling portion 29. The coupling portion 29 is formed of asynthetic resin filled into a runner in the mold assembly of theinjection compression molding machine. A supported portion 30 extendsfrom the coupling portion 29, the supported portion being placed upwardwhen the injection molded product 28 is dipped into the hard coatingliquid 21. The supported portion 30 is formed by filling synthetic resinin a hollow space adjacent to the runner in the mold assembly.

Each of the lens portions 28A is provided with a bar-shaped liquidguiding and collecting area 28C on an opposite side to the supportedportion 30 on the periphery of the lens portion.

When the injection molded product 28 is dipped into the hard coatingliquid 21, the supported portion 30 projecting upward is supported withthe supporting utensil 20. As a result, two pieces of the lens portions28A are dipped into the hard coating liquid 21 at the same time.Moreover, since all the liquid collecting and guiding areas 28C aredisposed downward when pulled up, the hard coat liquid flowing down onthe surfaces of each lens portion 28A is guided to the liquid guidingand collecting area 28C for dripping down and a small amount of theremaining liquid without dripping down forms a liquid collected portionin the liquid guiding and collecting area 28C in the same way as theabove-described embodiment.

FIG. 6 shows a trial lens 48″ according to still another embodiment. Thetrial lens 48″ is formed from a secondary injection molded product 48′in FIG. 7 obtained from a primary injection molded product 48 in FIG. 9.The secondary injection molded product 48′ is provided with a lensportion 48A, a grip portion 48B molded on a periphery of the lensportion 48A simultaneously with the lens portion 48A and a bar-shapedsupported portion 48C formed on the opposite side to the grip portion48B on the periphery of the lens portion 48A. The supported portion 48Cis a portion supported with the supporting utensil when the injectionmolded product 48′ is treated with a coating, and molded simultaneouslywith the lens portion 48A and the grip portion 48B. Consequently, theprocess of molding the injection molded product 48′ including thesupported portion 48C is simplified.

The lens portion 48A is a progressive multifocal lens portion having aportion for far vision E, a portion for near vision F, and a progressiveportion G between the portion for far vision E and the portion for nearvision F. In FIG. 7, an eye point of the portion for far vision E isrepresented by H and an eye point of the portion of near vision F isrepresented by I, respectively.

The grip portion 48B is provided with an indication 49 fordistinguishing between the right and the left which shows the lensportion 48A in the injection molded product 48′ is for a right eye or aleft eye, and an addition indication 50 which shows the addition of thelens portion 48A in the injection molded product 48′. The indications 49and 50 are formed with a mark engraved on a member composing the moldassembly in the injection compression molding machine when the gripportion 48B is molded simultaneously with the lens portion 48A.

As shown in FIG. 8, integrally molded with the lens portion 48A on theperiphery of the lens portion 48A is an edge portion 48D which, as wellas the grip portion 48B and the supported portion 48C, is moldedsimultaneously with the lens portion 48A. The edge portion 48D isdivided from the portions for far vision E and near vision F in the lensportion 48A respectively by a step 51 and a groove 52. The edge portion48D which is thicker than the portion for near vision F is substitutedfor the holder ring 22 shown in FIG. 4.

Consequently, the trial lens 48″ shown in FIG. 6 according to theembodiment becomes more lightweight than the trial lens 18″ in FIG. 4 inwhich the holder ring 22 is attached on the periphery of the lensportion 18A.

The grip portion 48B shown in FIG. 7 is formed shifting to the right orthe left at an angle of 45 degrees from the center between the rightportion and the left portion of the lens portion 48A according towhether the lens portion 48A in the injection molded product 48′ ismanufactured for a right eye or a left eye. That is, when the trial lens48″ obtained from the injection molded product 48′ is manufactured for aleft eye, the grip portion 48B is formed at an angle of 45 degrees tothe left of the lens portion 48A as seen from a testee who wears trialframes 24 in FIG. 6, and when the trial lens 48″ is manufactured for aright eye, the grip portion 48A is formed at an angle of 45 degrees tothe right of the lens portion 48A as seen from a testee. The lensportion 48A of the injection molded product 48′ in FIG. 7 ismanufactured for a left eye.

In the edge portion 48D on the periphery of the lens portion 48A, marks53 showing the direction of a horizontal datum line J are formed inpoints located on both sides of the lens portion 48A when the lensportion 48A is disposed in a correct vertical direction as FIG. 7 shows.The marks 53 are portions indented in some points of the edge portion48D and molded by means of projected portions formed in a componentmember of the mold assembly simultaneously with the lens portion 48A,the grip portion 48B, the supported portion 48C, and the edge portion48D.

The marks 53 show the horizontal direction of the lens portion 48A andthe grip portion 48B shows the lens portion 48A is for a right eye or aleft eye so that the trial lenses 48″ for a right eye and a left eye canbe distinguished while a position of the revolving direction of thecircular lens portion 48A of each trial lens 48″ is accurately fixedwhen the trial lens 48″ obtained from the injection molded product 48′is set in the trial frames 24 in FIG. 6. Consequently, the trial lenses48″ can be correctly set in the trial frames 24. In addition, a dioptermeasuring position in the portions for far vision E and near vision F inthe lens portion 48A or layout of optical center can be easily known.

The above-described trial lens 48″ shown in FIG. 6 is 38 millimeters inthe whole diameter including the edge portion 48D, the edge portion 48is 1.5 millimeters in width, the lens portion 48A is 35 millimeters indiameter, and the grip portion 48B is 15 millimeters in length and 9millimeters in width.

The primary injection molded product 48 shown in FIG. 9 is manufacturedto obtain a total of ten secondary injection molded products 48′ forprogressive multifocal lenses arranged connectingly to each othertwo-dimensionally. The progressive multifocal lenses have five kinds ofadditions ranging from 1.00 diopter to 3.00 diopter at an interval of0.5 diopter pitch. Every two injection molded products 48′ have the lensportions 48A with the same addition.

Each secondary injection molded product 48′ is obtained by being cutfrom the primary injection molded product 48 at a forward end of thegrip portion 48B. Thereafter, a total of five secondary injection moldedproducts 48′ are hung supportively with a supporting utensil 54 shown inFIGS. 10 and 11 for coating. The supporting utensil 54 includes a body55 with five slots 55A formed upward from a lower surface into whichbar-shaped supported portions 48C of the injection molded products 48′can be inserted, and clipping members 57 composed of flat springs ofwhich the upper portions are fastened to the body 55 with screws 56, theclipping members being provided on every slot 55A. After the screws 56are loosened, the supported portions 48C of the injection moldedproducts 48′ are inserted into each slot 55A, the screws 56 aretightened, and hence each injection molded product 48′ is hungsupportively by the supported portion 48C being clipped with the body 55and the clipping member 57.

The supporting portion 54 is gripped with a gripping utensil 58. In thissituation, the injection molded products 48′ are dipped into and pulledup from the hard coating liquid 21 that is the coating liquid. Thedipping process is conducted by placing the supported portions 48Cupward and the grip portions 48C downward. In this embodiment, a surplusof hard coating liquid flowing down on surfaces of the lens portion 48Ais guided to the grip portion 48B for dripping down and the remaininghard coating liquid without dripping down forms a liquid collectedportion in the grip portion 48B, that is, in this embodiment the gripportion 48B also serves as a liquid guiding and collecting area.

The injected molded product is treated dipping as described above andthen heat-dried, thereby making a coating film with the hard coatingliquid on the surfaces of the lens portion 48A. Afterward, the supportedposition 48 is removed by cutting and a label mentioning the sameinformation as the foregoing indications 49 and 50 shown in the gripportion 48B is stuck to the grip portion 48B, thereby finishing thetrial lens 48″ in FIG. 6.

When the supported portion 48C is removed by cutting, the supportedportion 48 is shaped into a bar extending in an outside diametricaldirection of the lens portion 48A with a small connecting area with theedge portion 48D on the periphery of the lens portion 48A, whichfacilitates the cutting process.

The grip portion 48B which also serves as the liquid guiding andcollecting area is formed on the periphery of the lens portion 48A onthe side of the portion for far vision E out of the sides of portionsfor far vision E and near vision F in the lens portion 48A. If the gripportion 48B is formed on the periphery of the lens portion 48 on theside of the portion for near vision F, since the groove 52 is formeddepending a sectional shape of the portion for near vision F between theportion for near vision F and the edge portion 48C as shown in FIG. 8,the hard coating liquid is collected in the groove 52 when the injectionmolded product is pulled up from the hard coating liquid, which affectsthe optical precision of the lens portion 48A. However, this embodimentcan prevent the disadvantage described above the breaking out.

FIGS. 12 and 13 show a mold assembly in an injection compression moldingmachine for molding the primary injection molded product 48 in FIG. 9.The mold assembly is provided with a top mold 61 and a bottom mold 62,both of which a parting line PL divides. The top mold 61 contains aninner insert member 63, an outer insert member 64 disposed on theoutside of the inner insert member 63, and a back insert 65 disposed onthe back side of the inner insert member 63, in other words, on theupper side of the inner insert member 63. The bottom mold 62 contains aninner insert member 66, an outer insert member 67 disposed on theoutside of the inner insert member 66 which is built in a hollow portion67A, and a spacer 68 for adjusting the thickness of a lens disposed onthe back side of the inner insert member 66, in other words, on thelower side of the inner insert member 66, and between the inner insertmember 66 and the outer insert member 67.

The inner insert member 63 in the top mold 61 and the inner insertmember 66 in the bottom mold 62 are vertically disposed opposite to eachother. The outer insert member 64 in the top mold 61 and the outerinsert member 67 in the bottom mold 62 are also vertically disposedopposite to each other. An insert 61A in the top mold 61 is formed withthe inner and the outer insert members 63 and 64 in the top mold 61, anda corresponding insert 62A in the bottom mold 62 is formed with theinner and the outer insert members 66 and 67 in the bottom mold 62. Thenumber of a pair of the inserts 61A and 62A disposed vertically is thesame as the number of sets of the secondary injection molded products48′ manufactured from the primary injection molded product 48 shown inFIG. 9. When the top mold 61 and the bottom mold 62 are mold-closed, acavity 69 is formed between a pair of inserts 61A and 62A disposedvertically in each set, the cavity 69 containing a lens molded portion69A, a grip molded portion 69B, and a supported portion molded portion69C.

The lens molded portion 69A is formed between the inner insert members63 and 66 in the top and the bottom molds 61 and 62, respectively. Thegrip molded portion 69B and the supported portion molded portion 69C areformed between the outer insert members 64 and 67 in the top and thebottom molds 61 and 62, respectively. An engraving mark member 70 isdisposed on a spot corresponding to the grip molded portion 69B in theouter insert member 67 in the bottom mold 62. When the lens portion 48A,the grip portion 48B and the supported portion 48C in FIG. 7 are moldedby filling molten synthetic resin in a cavity 69, the indications 49 and50 are provided on the grip portion 48B by means of the engraving markmember 70.

As shown in FIG. 15, recessed portions 64A and 67A are formed in theouter inserts members 64 and 67 in the top and the bottom molds 61 and62, respectively. When the molten synthetic resin is filled in thecavity 69, the edge portion 48D serving as the holder ring is formed onthe periphery of the lens portion 48A as shown in FIGS. 7 and 8.Therefore, a space between the recessed portions 64A and 67A is an edgemolded portion 69D in the cavity 69. Moreover, provided in the outerinsert member 67 in the bottom mold 62 is a projection to form the mark53 with the dented portion shown in FIG. 7 on the edge portion 48D.

As shown in FIG. 12, the back insert 65 is integrally provided with amale screw portion 65A extending downward. The back insert 65 and theinner insert member 63 are joined together by the male screw portion 65Abeing tightened into a hole of a female screw. As shown in FIG. 13, theinner insert member 66 in the bottom mold 62 is joined to the outerinsert member 67 with a bolt 71.

The lens portion 48A molded in the lens molded portion 69A in the cavity69 is a meniscus lens of which one surface is a concave surface from aspherical surface and the other surface is a convex surface from anaspherical surface. The concave surfaces of the lens portions 48A formedwith the inner insert members 63 in the top mold 61 have the same curvedsurface in the progressive multifocal lenses with different additions.However, the convex surfaces of the lens portions 48A formed with theinner insert members 66 in the bottom mold 62 are required to havedifferent curved surfaces in the progressive multifocal lenses withdifferent additions. Therefore in the mold assembly according to theembodiment, five kinds of the inner insert members 66 are used to moldfive kinds of progressive multifocal lenses as described above. Theinner insert members 66 are positioned in the outer inserts 67 with apositioning pin 72 in FIG. 13 so that the inner insert members 66 areaccurately located in the outer insert members 67 in a direction ofrotation on a vertical axis.

The top mold 61 is vertically separated by a boundary section K—Kbetween a mold plate 73 and a mold plate 74. When the top mold 61 andthe bottom mold 62 are mold-closed, in relation to a portion below themold plate 73 a portion above the mold plate 74 can vertically move incorrespondence to a margin for compressing with a clamping cylinder andanother cylinder. The back insert 65 and the inner insert member 63 inthe top mold 61 are members joined to the mold plate 74 as shown clearlyin FIG. 12 so that the back insert 65 and the inner insert member 63vertically move with the mold plate 74.

When the top mold 61 and the bottom mold 62 are mold-closed, the moltensynthetic resin is injected from an injection nozzle 80 shown in FIG. 12in the injection compression molding machine. Subsequently, the moltensynthetic resin is filled in each cavity 69 through a sprue 81, a runner82, and a gate 83 inside the mold assembly. At this time, the backinsert 65 and the inner insert member 63 rise in correspondence to themargin for compressing. After the molten synthetic resin is filled inthe cavity 69, the back insert 65 and the inner insert member 63descend. Thus is compressed the molten synthetic resin which isgradually cooled and solidified by a temperature controlling fluidpassing through fluid flowing passages 84 in the top mold 61 and thebottom mold 62.

After the injection molded product 48 in FIG. 9 is molded bysolidification of the molten synthetic resin, the top mold 61 and thebottom mold 62 are mold-opened from a paring line PL and the injectionmolded product 48 attached to the side of the top mold 61 is pushed outby means of a pin 87 in an ejecting plate 86 which is pushed down with abar 85 in an ejecting cylinder.

The primary injection molded product 48 taken out from the mold assemblyas described above is provided with ten secondary injection moldedproducts 48′. Each secondary injection molded product 48′ is providedwith the lens portion 48A, the grip portion 48B, the supported portion48C and the edge portion 48D. The grip portion 48B, the supportedportion 48C and the edge portion 48D are molded simultaneously with thelens portion 48A. The indications 49 and 50 in FIG. 7 are provided inthe grip portion 48B and the mark 53 is formed in the edge portion 48D.

As shown in FIG. 12, the grip molded portion 69B for molding the gripportion 48B in the cavity 69 is formed between the gate 83 from whichthe molten synthetic resin flows into the cavity 69 and the lens moldedportion 69A in the cavity 69. Accordingly, when the molten syntheticresin flows into the cavity 69 from the gate 83, the molten syntheticresin is filled in the lens molded portion 69A through the grip moldedportion 69B so that distortion in the filling of the molten syntheticresin is easy to break out in a portion of the resin near the gate 83,but no distortion occurs in a portion of the resin filled in the lensmolded portion 69A, thus securing a high precision of the lens.

The inserts 61A and 62A making a pair which are disposed in the top mold61 and the bottom mold 62 are composed of the inner insert member 63 and66, and the outer insert members 64 and 67, respectively. The lensmolded portion 69A is formed with the inner insert members 63 and 66,and the grip molded portion 69B and the like are formed with the outerinserts members 64 and 67. Consequently, when more than one type oftrial lenses with different kinds, diopters, thicknesses and the like ofthe lens portions 48A provided with the grip portions 48B and the likeintegrally formed with the lens portions 48A on the periphery of thelens portions 48A are manufactured, only the inner insert members 63 and66 need to be exchanged, while the outer insert members 64 and 67 areused in common for all sorts of trial lenses.

In this embodiment, the spacer 68 for adjusting the thickness isdisposed on the back side of the inner insert member 66 in the bottommold 62 as described above. A portion of the spacer 68 is shown in FIG.15. The progressive multifocal lens portion 48A, which is molded in thelens molded portion 69A in the cavity 69, is provided with five kinds ofadditions ranging from 1.00 diopter to 3.00 diopter at intervals of 0.5pitch as stated above. A solid line L shown in FIG. 15 is a convexcurved line of the lens portion 48A with an addition of 2.00 diopter,two-dot chain line M is a convex curved line of the lens portion 48Awith an addition of 3.00 diopter, and two-dot chain line N is a convexcurved line of the lens portion 48A with an addition of 1.00 diopter.

The capacity of each cavity 69 to mold five kinds of the lens portions48A, that is, the volume of the lens portion differs in specificationsbased on the usual design of lenses. However, as the difference incapacity among the cavities 69 becomes larger, the difference in theamount of filling of the molten synthetic resin is enlarged, whichcauses an unevenness in molding conditions, and furthermore makes itdifficult to assure a high optical precision of the lens portions 48A tobe molded.

Consequently, in the embodiment, the volume of the lens portion with anintermediate addition of 2.00 diopter is a standard in the stage ofdesigning lenses. The thickness of other lens portions with otheradditions is modified to accord with the volume.

The aforesaid is explained from the side of the mold assemblyhereinafter. The spacers 68 with the same five kinds of thicknesses asadditions are used. A thickness T of the spacer 68 with the intermediatethickness is fixed as a thickness of the lens portion 48A with theintermediate addition of 2.00 diopter out of additions ranging from 1.00diopter to 3.00 diopter. The thickness of a spacer of the lens portion48A with an addition above 2.00 diopter and the thickness of a spacer ofthe lens portion 48A with an addition below 2.00 diopter are fixed onthe basis of the thickness T. Each of spacers 68 with five kinds ofthickness thus obtained is disposed on the back side of the inner insertmember 66 to mold the lens portion 48A with each addition.

As a result, when five kinds of progressive multifocal lens portions 48Awith different additions are manufactured at one shot by means of themold assembly in the injection compression molding machine, the capacityof each cavity 69 can be averaged so that molding conditions of eachlens portion 48A with each of the additions can be averaged, thusmanufacturing each of the lens portions 48A with a high opticalprecision.

To obtain the lens portion 48A with a pre-determined thickness, theposition of a lens molded surface in the inner insert member 63 in thetop mold 61 in relation to the inner insert member 66 in the bottom mold62 is located in the pre-determined vertical direction position, andhence, in the embodiment, the back insert 65 is disposed on the backside of the inner insert member 63 in the top mold 1 as shown in FIG.14.

In the embodiment, a length S1 of the inner insert member 63 has anerror compared with the original length and the initial length of theback insert 65 is a little larger than the original length. After theinner insert member 63 and the back insert 65 are joined with the malescrew portion 65A, an upper surface of the back insert 65 is cut toobtain the accurate vertical direction position of the lens moldedsurface 63A of the inner insert member 63 in the top mold 61 in relationto the inner insert member 66 in the bottom mold 62 by means of a totallength S2 of the inner insert member 63 and the back insert 65, then alength S3 of the back insert 65 is finished to obtain the total lengthS2.

Consequently, the accurate vertical directional position of the lensmolded surface 63A is fixed by the length of the back insert 65, andtherefore in the inner insert member 63 only the lens molded surface 63Aneeds to be high-precisely finished, which facilitates the work ofmanufacturing and processing the inner insert member 63.

When the length of the back insert 65 is S3, the thickness of a headportion 65B of the back insert 65 is the same as or a little larger thana depth of a recessed portion 73A in the mold plate 74. Thus, also whenthe back insert 65 is joined with the mold plate 74, the accuratevertical directional position of the lens molded surface 63A in theinner insert member 63 can be obtained, and in addition, detachment ofthe mold plates 73 and 74 to get the margin for compressing is possible.

Industrial Availability

As described above, a plastic trial lens, an injection molded productfor making the trial lens and a mold assembly for molding the injectionmolded product according to the present invention are useful since agrip portion is integrally formed on a periphery of a lens portion, thegrip portion being gripped when the plastic trial lens is set in trialframes for trial lenses.

What is claimed is:
 1. An injection molded product for making plastictrial lenses comprising: a lens portion; a liquid guiding and collectingarea integrally formed on a periphery of said lens portion, in whichcoating liquid flowing down on surfaces of the lens portion is guidedand collected when dipped into and pulled up from the coating liquid;and a grip portion gripped when said lens portion is set in the trialframes after said liquid guiding and collecting area is removed, saidliquid guided and collecting area and said grip portion being moldedsimultaneously with said lens portion.
 2. The injection molded productfor making the plastic trial lenses according to claim 1, wherein saidliquid guiding and collecting area is shaped into a bar extending in anoutside diametrical direction of said lens portion.
 3. The injectionmolded product for making the plastic trial lenses according to claims1, wherein said liquid guiding and collecting area and said grip portionare formed opposite to each other on the periphery of said lens portion.4. The injection molded product for making the plastic trial lensesaccording to claim 1, wherein a plurality of said lens portions arecoupled with each other by means of a coupling portion, the couplingportion being provided with a supported portion supported with asupporting utensil when said lens portions are dipped into the coatingliquid, and said liquid guiding and collecting area is formed on anopposite side to the supported portion on the periphery of each of saidlens portions.
 5. An injection molded product for making plastic triallenses comprising: a lens portion; and a grip portion molded on aperiphery of said lens portion simultaneously with the lens portionbeing gripped when said lens portion is set in trial frames for triallenses, the grip portion being disposed downward when said lens portionis dipped into coating liquid, thereby serving also as a liquid guidingand collecting area to guide and collect the coating liquid flowing downon surfaces of said lens portion when said lens portion is pulled upfrom the coating liquid.
 6. The injection molded product for making theplastic trial lenses according to claim 5, wherein said lens portion isa progressive multifocal lens portion with a portion for far vision, aportion for near vision, and a progressive portion between the portionfor far vision and the portion for near vision, and said grip portion isformed on a periphery of said lens portion on the side of the portionfor far vision out of the portion for far vision and the portion fornear vision.
 7. The injection molded product for making the plastictrial lenses according to claim 5, wherein a supported portion isprovided on the opposite side to said grip portion on the periphery ofsaid lens portion, the supported portion being supported with asupporting utensil when said lens portion is dipped into the coatingliquid.
 8. The injection molded product for making the plastic triallenses according to claim 5, wherein the supported portion is moldedsimultaneously with said lens portion and said grip portion.
 9. Theinjection molded product for making the plastic trial lenses accordingto claim 8, wherein the supported portion is shaped into a bar extendingin an outside diametrical direction of said lens portion.
 10. A plastictrial lens comprising: a lens portion; a grip portion formed on aperiphery of the lens portion; an edge portion provided integrally onthe periphery of the lens portion; and a mark provided on said edgeportion for indicating a direction of a horizontal datum line, whereinsaid lens portion is a progressive multifocal lens portion having a farvision portion, a near vision portion and a progressive portion providedbetween the far vision portion and the near vision portion, said gripportion being provided on the right or left periphery of the lensportion depending on whether the lens is for the right eye or a left eyeand said lens portion, grip portion, edge portion and mark are moldedsimultaneously when they are molded by an injection compression moldingmethod.
 11. The plastic trial lens of claim 10, wherein said lensportion has a convex surface which is a meniscus lens having an asphericprogressive surface and a spherical concave surface.
 12. The plastictrial lens of claim 11, wherein the curvature of the concave surface isfixed.
 13. A plastic trial lens comprising: a lens portion; a gripportion formed integrally on the periphery of the lens portion for beinggripped when the lens portion is set in glass frames; an edge portionprovided integrally on the periphery of the lens portion in place of aholder ring; and a mark provided in the form of an indented portionprovided in the edge portion for indicating a horizontal datum line,wherein said lens portion is a progressive multifocal lens portionhaving a far vision portion, a near vision portion and a progressiveportion provided between the far vision portion and the near visionportion, said grip portion is provided on the right or left periphery ofthe lens portion depending on whether the lens is for a right eye or aleft eye and said lens portion, grip portion, edge portion and mark aremolded simultaneously when they are molded by an injection compressionmolding method.
 14. The plastic trial lens of claim 13, wherein saidlens portion has a convex surface which is a meniscus lens having anaspheric progressive surface and a spherical concave surface.
 15. Theplastic trial lens of claim 14, wherein the curvature of the concavesurface is fixed.